The aviation security industry has a clear and pressing need for improvements in security effectiveness while reducing costs of operations. There has been a vastly increased emphasis on improving national security since the terrorist attacks of Sep. 11, 2001. Current article screening methods at entry points to secure areas in airports and other security sensitive installations are essentially manual systems that take a little advantage of today's computerized technologies. Typically, situated at the entry to an airport concourse, for instance, is a security checkpoint station having x-ray scanners for inspection of carried articles. An x-ray image inspector (screener) who examines the x-ray images of articles passing through a scanner is stationed at each scanner. The screener regulates the motion of articles through the scanner by cycling on and off the conveyor belt that transports articles through the scanner. In a typical sequence the screener will energize the conveyor belt and transport an article into the scanner and through the scanning zone within the scanner. A typical sized article will remain within the confines of the scanner but near the exit from the scanner as it clears the scanning zone. An x-ray image is generated and displayed on a monitor screen for the screener to examine. The screener normally will then de-energize the conveyor belt and hold the article within the confines of the scanner while examining the x-ray image. Holding the article in the confines of the scanner allows the screener to maintain physical control over the article until the article is cleared through examination of its x-ray image.
If the screener does not see any suspect items in the x-ray image, then the screener will energize the conveyor belt and pass the article out of the scanner making it accessible to passengers so that it can be retrieved and carried away from the security checkpoint by its associated passenger. If a screener sees a suspect item in an x-ray image of an article, the screener typically suspends image scanning and inspection and orally alerts search personnel stationed in the vicinity of the x-ray machine conveyor to remove the article in question from the scanner to search for the object. However, it is possible for the screener to lose control of the article and not know where it is located within the system. For example, a screener can forget to de-energize the conveyor belt and inadvertently allow an article to pass through the scanning zone and out of the scanner, unbeknown to the screener, while the screener examines the stationary x-ray image of the article on the scanner monitor screen. Once the article is out of the scanner it can be accessed by passengers and picked up and carried away before its x-ray image has been cleared. In such cases the Transportation Security Administration (TSA) security personnel at an airport have been known to close the airport concourse where the article was not properly screened, empty the concourse of passengers and their carried articles, and re-screen all passengers and their carried articles resulting in a major delay in airplane departures from the airport thereby adversely affecting flight operations throughout the airport system. Such unfortunate events are not infrequent and are very disruptive and costly.
As an article is transported through an x-ray scanner, an x-ray image of the article is generated and displayed on a visual monitor in order for a screener to examine the x-ray image for potential prohibited items, contraband, or the like. A typical scanner will scroll its x-ray image onto the monitor screen as an article moves through the scanning zone within the scanner and the x-ray image is generated responsive to electronic signals received from detectors within the scanning zone. As the article clears the scanning zone the scanner system by design may then freeze the x-ray image on the monitor screen so that image inspection can take place because visual image inspection is difficult to perform on a moving image and the screener must have adequate time to examine the x-ray image before it leaves the screen. In this case the x-ray image stays motionless on the monitor screen, regardless of conveyor belt motion, until a subsequent article enters the scanning zone and a new x-ray image is generated and scrolled onto the monitor screen. Typical scanners are designed such that the movement of x-ray images onto, across, and off the monitor screen is related to the rate of introduction of articles to be scanned into the scanner and not to the motion of the scanner transport conveyor through the scanner. This design feature at times can be confusing to the screener in that there is a natural tendency for a person, such as a screener, to relate the motion of the x-ray image scrolling on the screen to the transport motion through the scanner of the article being x-rayed. Thus, when the scanner freezes the motion of the x-ray image on the screen a screener can subconsciously, and erroneously, interpret this as the transport conveyor stopping its motion. The conveyor belt motion may then continue while the screener thinks it has stopped and convey the article out of the scanner while the article's x-ray image is being inspected.
For example, assume a case where a first article is transported on the conveyor into the scanner zone at a typical conveyor speed of 9 inches/sec. A second article is not placed onto the conveyor belt at the input to the scanner by another passenger until 20 seconds later. As the first article passes through the scanning zone within the scanner, an x-ray image of it scrolls onto the monitor screen. As the article clears the scanning zone, the image will stop scrolling across the screen and remain motionless until the next (second) article enters the scanning zone. The screener, who normally would turn off the conveyor belt, forgets in this example to turn it off and the motionless x-ray image on the screen lulls the screener into thinking the conveyor belt is stopped. The screener, seeing a potential suspect item within the x-ray image, is closely examining the x-ray image when suddenly it scrolls across the screen as the second article moves into the scanner zone. The screener then realizes that the belt was not stopped while the screener was examining the x-ray image of the first article during which time the first article has moved 15 ft out of the scanner into the passenger pickup area. In trying to find the first article with the suspect item somewhere in the passenger pickup area the screener, not knowing what the article physically looks like, realizes that a passenger may have already retrieved it and left the area and is somewhere in the concourse. The TSA then may clear the concourse of all passengers and their carried articles and all must be re-screened.
What is needed to help prevent such mistakes is a system that informs security personnel of the physical location of articles whose x-ray images are displayed on the scanner monitor screen, that alerts the screener and/or other security personnel when an article is moving out of the confines of the scanner, and that can present photographs of the articles correlated with their x-ray images on the monitor screen to help in article identification. The present invention provides these capabilities.